Alauddin Khilji NEVER ventured until Kandahar. His kingdom ended at river Indus. Multan was west border of Khilji.

Even Peshawar belonged to the Mongols.
In those days, Kandahar was known as "Tiginabad" & it was firmly in the hands of Mongols.

The region of Afghanistan, including Khilji's own homeland Khalj, was in the hands of Mongol commander Qatlagh Qocha followed by his successor Daud Qocha.

They frequently raided Punjab.
.............................................................................................................
territories but most of Qaidu's also. Within a few years, however, this calm was dissipated by events that had their roots, once more, in the frontier zone of Afghanistan. After the brief rule of Esen Buqa's younger brother It Qul over the Negtideris, we find the region under the control of Daud Qocha, the son or nephew of Qutlugh Qocha. Like Qutlugh Qocha himself, Daud Qocha moved between the banks of the Oxus and 'the furthest parts of Shaburghan', on the one hand, and the hot regions (garmsir) of Ghazna, Bini-yi Gaw, Bust, Tiginabad and the Indus valley on the other. He proved an energetic ruler, nourishing designs on Herat and attempting to bring to heel two chiefs, Abachi's sons Tem& and *Lakchir. Since they are described as leading 'the remnants (baqaya) of the Negaderis', it may be that part of the Neguderi forces had profited from the recent upheavals to escape from the Chaghadayid orbit. At any rate, Temur and *Lakchir sought help from the Ilkhan Oljeitu, whose forces in 712/1312 fell on Daud Qocha and sacked his headquarters at Tiginabaad.
.............................................................................................................
Over the next few years Mongol bands numbering 10,000 or 15,000 horse continued to make plundering raids on the Panjab, but caused no general alarm and retired on each occasion without a pitched battle. But when in 702/1302-3 'Ala' al-Din's forces were again scattered on distant campaigns, Taraghai, now in command of Qutlugh Qocha's army, felt strong enough to threaten Delhi a second time. This invasion appears to have posed an even greater danger than that of Qutlugh Qocha. 'Ala' al-Din was reduced to following the defensive tactics he had eschewed during the earlier attack, barricading himself and his army in the Siri plain. The Mongols' position extended from the Yamuna as far as the plain of Lohrawat; but although they launched raids into the suburbs of the old city, where they penetrated as far as the Hawd-i Khass, they were unable to move there in force for fear of exposing their flank. This stalemate situation lasted for about two months; then Taraghai suddenly withdrew to his own territory.
.............................................................................................................

Regarding Khiljis "saving" India:

Khilji's father himself ran away to India to save himself from Mongols.

Mongols conquered ancestral Khilji lands in Central Afghanistan. Khilji & his father could do nothing.

Today, no Khiljis there. You find Hazaras with Mongol features.
This "Khilji defeated Mongols" trope has been trumped out of sense and reality. Here is a fact check.

Khilji NEVER defeated the Great Mongol empire. The Great Mongol empire disintegrated in 1259 after the death of Mongke Khan, 4 decades before Alauddin Khilji even became king.
After the disintegration of the Great Mongol Empire, a small breakaway faction known as "Chagatai Khanate" was formed whose kings claimed descent from royal Mongol line.

It was with this small Chagatai faction that Allauddin khilji waged wars. And every war was defensive.
Khiljis themselves were refugees who fled Afghanistan in the wake of Mongol conquests and found employment with Delhi Sultanate.

Throughout Khilji's reign, Chagatai Khanate held ancestral Khilji lands in Afghanistan and there was nothing Khilji could do about it.
Khilji's empire ended at Indus. All regions to the north and west of Indus were controlled by Chagatai Khanate.

Thus, all the ancestral homelands of Pashtuns, Afghans and Khiljis were held by Non Muslim Kafir Chagatais.

Khilji couldn't even dream of liberating his own homeland.
Chagatais sent a few raid parties across Indus into Alauddin Khalji's Kingdom. Because Chagatais were nomadic horse archers, they were quite ineffective against Khilji's forts and siege engines.

By "grinding down Hindus & reducing them to abject poverty" in his own words.

Khilji's rules

1) No Hindu should hold up his head

2) No Gold/Silver should be seen in houses of Hindus.
.............................................................................................................
.............................................................................................................

Continuing Khilji's rules for Hindus

3)Every Hindu, whether rich of poor, had to pay 50% of produce to the state.

4)Every animal grazed by Hindus was taxed irrespective of poor or rich.

Apart from looting Hindus & subjecting them to poverty, what else did Khilji do to keep prices low.

Of course, punishments!

Khilji fixed the price. Any Hindu trader who did not sell at that price was flogged.

If a trader kept a low weight, flesh was cut off from his buttocks.
.............................................................................................................
.............................................................................................................